implement Dhcp; ## configure an interface using DHCP# include "sys.m";	sys: Sys; include "draw.m"; include "ip.m";	ip: IP;	IPv4off, IPaddrlen: import IP;	IPaddr: import ip;	get2, get4, put2, put4: import ip; include "dhcp.m";	dhcpclient: Dhcpclient;	Bootconf, Lease: import dhcpclient; include "arg.m"; Dhcp: module{	init:	fn(nil: ref Draw->Context, nil: list of string);}; RetryTime: con 10*1000;	# msec init(nil: ref Draw->Context, args: list of string){	sys = load Sys Sys->PATH;	ip = load IP IP->PATH;	dhcpclient = load Dhcpclient Dhcpclient->PATH; 	sys->pctl(Sys->NEWFD|Sys->NEWPGRP, 0 :: 1 :: 2 :: nil); 	arg := load Arg Arg->PATH;	arg->init(args);	arg->setusage("dhcp [-bdmnpr] [-g ipgw] [-h hostname] [-x /net] ifcdir [ip [ipmask]]");	trace := 0;	pcfg := 0;	bootp := 0;	monitor := 0;	retry := 0;	noctl := 0;	netdir := "/net";	cfg := Bootconf.new();	while((o := arg->opt()) != 0)		case o {		'b' =>	bootp = 1;		'd' =>	trace++;		'g' =>	cfg.ipgw = arg->earg();		'h' =>	cfg.puts(Dhcpclient->Ohostname, arg->earg());		'm' =>	monitor = 1;		'n' =>	noctl = 1;		'p' =>	pcfg = 1;		'r' =>		retry = 1;		'x' =>	netdir = arg->earg();		* =>		arg->usage();		}	args = arg->argv();	if(len args == 0)		arg->usage(); 	ifcdir := hd args;	args = tl args;	if(args != nil){		cfg.ip = hd args;		args = tl args;		if(args != nil){			cfg.ipmask = hd args;			args = tl args;			if(args != nil)				arg->usage();		}	}	arg = nil; 	ifcctl: ref Sys->FD;	if(noctl == 0){		ifcctl = sys->open(ifcdir+"/ctl", Sys->OWRITE);		if(ifcctl == nil)			err(sys->sprint("cannot open %s/ctl: %r", ifcdir));	}	etherdir := finddev(ifcdir);	if(etherdir == nil)		err(sys->sprint("cannot find network device in %s/status: %r", ifcdir));	if(etherdir[0] != '/' && etherdir[0] != '#')		etherdir = netdir+"/"+etherdir; 	ip->init();	dhcpclient->init();	dhcpclient->tracing(trace);	e: string;	lease: ref Lease;	for(;;){		if(bootp){			(cfg, e) = dhcpclient->bootp(netdir, ifcctl, etherdir+"/addr", cfg);			if(e == nil){				if(cfg != nil)					dhcpclient->applycfg(netdir, ifcctl, cfg);				if(pcfg)					printcfg(cfg);				break;			}		}else{			(cfg, lease, e) = dhcpclient->dhcp(netdir, ifcctl, etherdir+"/addr", cfg, nil);	# last is array of int options			if(e == nil){				if(pcfg)					printcfg(cfg);				if(cfg.lease > 0 && monitor)					leasemon(lease.configs, pcfg);				break;			}		}		if(!retry)			err("failed to configure network: "+e);		sys->fprint(sys->fildes(2), "dhcp: failed to configure network: %s; retrying", e);		sys->sleep(RetryTime);	}} leasemon(configs: chan of (ref Bootconf, string), pcfg: int){	for(;;){		(cfg, e) := <-configs;		if(e != nil)			sys->fprint(sys->fildes(2), "dhcp: %s", e);		if(pcfg)			printcfg(cfg);	}} printcfg(cfg: ref Bootconf){	sys->print("ip=%s ipmask=%s ipgw=%s iplease=%d\n", cfg.ip, cfg.ipmask, cfg.ipgw, cfg.lease);} finddev(ifcdir: string): string{	fd := sys->open(ifcdir+"/status", Sys->OREAD);	if(fd == nil)		return nil;	buf := array[1024] of byte;	n := sys->read(fd, buf, len buf);	if(n < 0)		return nil;	(nf, l) := sys->tokenize(string buf[0:n], " \n");	if(nf < 2){		sys->werrstr("unexpected format for status file");		return nil;	}	return hd tl l;} err(s: string){	sys->fprint(sys->fildes(2), "dhcp: %s\n", s);	raise "fail:error";}